The full scale of the human cost already paid for the war on Iraq is only now becoming clear. Last week's estimate by investigators, using credible methodology, that more than 100,000 Iraqi civilians - most of them women and children - have died since the US-led invasion is a profound moral indictment of our countries.

The US and British governments quickly moved to cast doubt on the Lancet medical journal findings, citing other studies. These mainly media-based reports put the number of Iraqi civilian deaths at about 15,000 - although the basis for such an endorsement is unclear, since neither the US nor the UK admits to collecting data on Iraqi civilian casualties.

Civilian deaths have always been a tragic reality of modern war. But the conflict in Iraq was supposed to be different - US and British forces were dispatched to liberate the Iraqi people, not impose their own tyranny of violence.

Reading accounts of the US-led invasion, one is struck by the constant, almost casual, reference to civilian deaths. Soldiers and marines speak of destroying hundreds, if not thousands, of vehicles that turned out to be crammed with civilians. US marines acknowledged in the aftermath of the early, bloody battle for Nassiriya that their artillery and air power had pounded civilian areas in a blind effort to suppress insurgents thought to be holed up in the city. The infamous "shock and awe" bombing of Baghdad produced hundreds of deaths, as did the 3rd Infantry Division's "Thunder Run", an armoured thrust in Baghdad that slaughtered everyone in its path.

It is true that, with only a few exceptions, civilians who died as a result of ground combat were not deliberately targeted, but were caught up in the machinery of modern warfare. But when the same claim is made about civilians killed in aerial attacks (the Lancet study estimates that most of civilian deaths were the result of air attacks), the comparison quickly falls apart. Helicopter engagements apart, most aerial bombardment is deliberate and pre-planned. US and British military officials like to brag about the accuracy of the "precision" munitions used in these strikes, claiming this makes the kind of modern warfare practised by the coalition in Iraq the most humanitarian in history.

But there is nothing humanitarian about explosives once they detonate near civilians, or about a bomb guided to the wrong target. Dozens of civilians were killed during the vain effort to eliminate Saddam Hussein with "pinpoint" air strikes, and hundreds have perished in the campaign to eliminate alleged terrorist targets in Fallujah. A "smart bomb" is only as good as the data used to direct it. And the abysmal quality of the intelligence used has made the smartest of bombs just as dumb and indiscriminate as those, for example, dropped during the second world war.

The fact that most bombing missions in Iraq today are pre-planned, with targets allegedly carefully vetted, further indicts those who wage this war in the name of freedom. If these targets are so precise, then those selecting them cannot escape the fact that they are deliberately targeting innocent civilians at the same time as they seek to destroy their intended foe. Some would dismiss these civilians as "collateral damage". But we must keep in mind that the British and US governments made a deliberate decision to enter into a conflict of their choosing, not one that was thrust upon them. We invaded Iraq to free Iraqis from a dictator who, by some accounts, oversaw the killing of about 300,000 of his subjects - although no one has been able to verify more than a small fraction of the figure. If it is correct, it took Saddam decades to reach such a horrific statistic. The US and UK have, it seems, reached a third of that total in just 18 months.

Meanwhile, the latest scandal over missing nuclear-related high explosives in Iraq (traced and controlled under the UN inspections regime) only underscores the utter deceitfulness of the Bush-Blair argument for the war.

Having claimed the uncertainty surrounding Iraq's WMD capability constituted a threat that could not go unchallenged in a post-9/11 world, one would have expected the two leaders to insist on a military course of action that brought under immediate coalition control any aspect of potential WMD capability, especially relating to any possible nuclear threat. That the US military did not have a dedicated force to locate and neutralize these explosives underscores the fact that both Bush and Blair knew that there was no threat from Iraq, nuclear or otherwise.

Of course, the US and Britain have a history of turning a blind eye to Iraqi suffering when it suits their political purposes. During the 1990s, hundreds of thousands are estimated by the UN to have died as a result of sanctions. Throughout that time, the US and the UK maintained the fiction that this was the fault of Saddam Hussein, who refused to give up his WMD. We now know that Saddam had disarmed and those deaths were the responsibility of the US and Britain, which refused to lift sanctions.

There are many culpable individuals and organizations history will hold to account for the war - from deceitful politicians and journalists to acquiescent military professionals and silent citizens of the world's democracies. As the evidence has piled up confirming what I and others had reported - that Iraq was already disarmed by the late 1990s - my personal vote for one of the most culpable individuals would go to Hans Blix, who headed the UN weapons inspection team in the run-up to war.

He had the power if not to prevent, at least to forestall a war with Iraq. Blix knew that Iraq was disarmed, but in his mealy-mouthed testimony to the UN Security Council helped provide fodder for war. His failure to stand up to the lies used by Bush and Blair to sell the Iraq war must brand him a moral and intellectual coward.

But we all are moral cowards when it comes to Iraq. Our collective inability to summon the requisite shame and rage when confronted by an estimate of 100,000 dead Iraqi civilians in the prosecution of an illegal and unjust war not only condemns us, but adds credibility to those who oppose us.

The fact that a criminal such as Osama bin Laden can broadcast a videotape on the eve of the US presidential election in which his message is viewed by many around the world as a sober argument in support of his cause is the harshest indictment of the failure of the US and Britain to implement sound policy in the aftermath of 9/11.

The death of 3,000 civilians on that horrible day represented a tragedy of huge proportions. Our continued indifference to a war that has slaughtered so many Iraqi civilians, and will continue to kill more, is in many ways an even greater tragedy: not only in terms of scale, but also because these deaths were inflicted by our own hand in the course of an action that has no defence.-Dawn/The Guardian News Service.

(The writer was a senior UN weapons inspector in Iraq between 1991 and 1998)